Although a number of studies have been conducted on the immunology of malaria, fewer have been attempted using the exoerythrocytic stages either because of their availability or the complicating factor of extraneous tissue antigen contamination. Having acquired the cell culture expertise developed in Huff's laboratory at the Naval Medical Research Institute, we are able to grow sufficient quantities of the exoerythrocytic stages to do both in vitro and in vivo studies related to immunity. Isolation, purification, and concentration of these exo-stage parasites allow development of optimal immunization regimens, exploration of enhancing procedures, and subsequent monitoring of these attempts by in vivo and in vitro testing.